(a) Field of the Invention
The present invention relates to an electronic musical instrument wherein tones are produced by computing the amplitudes, at successive sample points, of a complex waveshape and aligning these amplitudes one after another in time sequence to form musical tone waves as the computations are carried out.
(B) Brief Description of the Prior Art
In U.S. Pat. No. 3,809,786 entitled COMPUTOR ORGAN is disclosed an electronic musical instrument wherein the amplitudes at successive sample points of a musical waveshape are computed, and the amplitudes are aligned in time sequence to form musical tone waves as the computations are carried out. In the musical instrument, a discrete Fourier algorithm is implemented to calculate the individual harmonic components at each sample point, using a stored set of harmonic coefficients which characterize the resultant waveshape. For each sample point, the amplitudes of plural harmonic components are calculated individually by multiplying the coefficient associated with each harmonic by a sine value related to the sample point which value is read out of a sinusoidal table memory.
Such a prior art instrument needs several large capacity memories for storing the harmonic coefficients and the sinusoidal table in order to attain a realistic simulation of existing instrument sounds such as of an air-driven organ pipe, piano, flute, horn, or string, and it also needs a complex means for programatically scaling the harmonic coefficients with the lapse of time to obtain the attack, decay and other amplitude transient effects.